Humidity Change and Unisons

Ron Nossaman RNossaman@KSCABLE.com
Sun, 20 Aug 2000 22:31:07 -0500


>Hi Ron,
>
>I agree there is a great deal going on--but when one observes 20 pianos or
>a 100 all doing the same sort of humidity dance, it certainly points out
>the need of humidity control.
>Regards,
>Don Rose, B.Mus., A.M.U.S., A.MUS., R.M.T., R.P.T.


Whoa Don! Where'd that come from? What the heck happened to why does this
do what this does? Humidity control is the default answer to nearly any
tuning stability issue there is. If that was what this was all about, it
could have been boiled down to that on the first post and saved a heck of a
lot of wildly speculative correspondence the last week. I was just trying
to put some sort of  minimal mysticism, physics supportable rationale to
your observation. The vast majority of what I tune needs better humidity
control than it will ever get if it lasts forever. I assume that's the case
for nearly everyone on the list, except for that guy in Shangra La, where
everything's perfect. Then again, he's probably starving for work. 

Look at the thing from a standpoint of friction points and length
proportions. Draw some pictures, assign some tension numbers to string
segments and friction values to bearing points, and think about what
happens to the tensions in the individual sections when the bridge top goes
up and down with humidity swings. Without any particular target in mind,
follow the numbers and logic and see where it takes you. Real world applied
physics takes into account every friction point and the tension in every
segment of every string, and we should at least attempt to do the same
thing if we have any hope of understanding what's happening. It gets pretty
involved, but it all seems to fit logically with what we observe in pianos
looking at just humidity and pitch after the fact.

I just can't accept the because of X, Y happens, unless there's some
rational cause and effect relationship. I guess it's just one of my many
personality flaws.

Ron N


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